A UV nanoimprint method is a patterning method of pressing a mold having a fine textured pattern on its surface against a substrate coated with a resist (photo-curable composition) and curing the resist to transfer the textured pattern to the resist film on the substrate.
It is important in the UV nanoimprint method to decrease the force with which the mold is released from cured resist, that is, demolding force. This is because a large demolding force may cause defects in the pattern or may cause the substrate to rise from the stage, resulting in low alignment precision.
A known curable composition for use in UV nanoimprint contains at least one polymerizable monomer, a polymerization initiator, and a fluorinated surfactant.
PTL 1 discloses a resist composition that contains a fluorinated surfactant having a hydrophilic ethylene oxide group (EO group) structure. PTL 1 discloses a resist composition that contains a fluorinated surfactant having an EO group structure so as to improve adhesion and mold releasability.
PTL 2 discloses a resist composition that contains a fluorinated surfactant having a chemical structure having a lipophilic propylene oxide group (PO group).
PTL 2 also discloses a resist composition that contains a fluorinated surfactant having both an EO group and a PO group in its molecular.
As described above, it is known that a fluorinated material may be added to a curable composition to impart water repellency to a surface of a photo-cured film and decrease demolding force. However, the addition of a known fluorinated material alone still results in a large demolding force.
Furthermore, an excessive addition of a fluorinated surfactant to reduce demolding force results in a decrease in surface tension and poor filling in a substrate or a mold.